Corner construction for folding boxes, particularly for corrugated boxes



2,718,998 PARTICULARLY Sept. 27, 1955 R. P. BEMISS CORNER CONSTRUCTION FoR FOLDING BOXES FoR CORRUGATED BOXES 4 Sheets-Sheet '1 Filed Aug. 29, 1950 Fig 1 Fig. 2

INVENTOR.

OBEIQT' PALMER BEMLSS A TTORNEY Sept. 27, 1955 R. P. BEMISS CORNER CONSTRUCTION FOR FOLDING BOXES, PARTICULARLY FOR CORRUGATED BOXES 4 Sheets-Sheet 2 Filed Aug. 29, 1950 INVENTOR.

ROBERT PALMER BEM/SS W's-W? ATTORNEY R. P. BEMISS 2,718,998

PARTICULARLY Sept. 27, 1955 CORNER CONSTRUCTION FOR FOLDING BOXES FOR CORRUGATED BOXES 4 Sheets-Sheet 3 Filed Aug. 29, 1950 JNVENTOR.

ROBERT F'ALMEPBEM/SS MA ATTORNEY Sept. 27, 1955 R. P. BEMISS 2,718,998

CORNER CONSTRUCTION FOR FOLDING BOXES, PARTICULARLY FOR CORRUGATED BOXES 4 Sheets-Sheet 4 Filed Aug. 29, 1950 Fig 8 IN VEN TOR.

PAL MER -BEM 155 R0 E T W'QW ATTORNEY United States Patent CORNER CONSTRUCTION FOR FOLDING BOXES, PARTICULARLY FOR CORRUGATED BOXES Robert Palmer Bemiss, Burlingame, Califi, assignor, by mesne assignments, to Baljak Corporation, Wilmington, Del., a corporation of Delaware Application August 29, 1950, Serial No. 182,015

6 Claims. (Cl. 229-35) This invention relates to improvements in cartons, boxes, trays, and other structures, hereinafter collective ly referred to as boxes or folding boxes, made by folding, from blanks of cardboard, solid fibre, paperboard, or other suitable foldable sheet material.

The invention has particular application to the type of folding boxes which are maintained in assembled condition by a glueless interengagement of certain portions of the box blank.

The art of assembling boxes by interengagement of the box blank without the use of adhesive is many decades old, and many different forms of locks have been proposed for forming box corners. The majority of the locks heretofore proposed are designed for hand assembly. Considerable difficulties are encountered, when it is attempted to set up and engage conventional locks by mechanical equipment. Other known forms of locks suited for assembled by machine generally require equipment which is complex or slow.

The present invention is concerned with certain improvements in the corner construction of folding boxes which result in a more secure lock than has heretofore been available, and a lock which can be formed on automatic high speed machinery of compact design and relatively simple construction, comprising, essentially a plunger and a die through which the plunger forces the box blank in the process of assembly.

More particularly, the invention provides a form of interlock which is admirably suited for assembling boxes made of corrugated board. The'glueless assembly of corrugated boxes presents particular problems due to the physical characteristics of corrugated board, among which stand out the relatively great thickness of the board and its low flexibility, as compared to non-corrugated board.

The invention provides an improved box corner construction which is most attractive in appearance, in that the flaps or tongues by which the interlock is formed, and which in known forms of locks are quite conspicuous, are arranged in such a way as to be practically concealed. This improvement opens an enlarged field of application to boxes of the glueless type which heretofore was closed, either because of consumers resistance to conspicuous flaps and tongues, or because of technical difficulties encountered with exposed flaps and tongues which interfere, at least in some measure, with the use of telescoping covers, the use of overwraps, the use of hinged covers, and the packaging of such boxes in larger receptacles because of the danger of flaps or tongues of one box becoming entangled with those of another. The present improvement also opens to boxes of the glueless type the large field of corrugated boxes which heretofore were generally assembled by stitching, gluing or taping.

The improved corner construction embodying the present invention may be incorporated in boxes of the square type as well as in boxes having slanted walls, such as trays or baskets.

' Boxes equipped with the improved corner lock may be set up, and the box walls be locked simultaneously at Patented Sept. 27, 1955 ICC all four or more corners, by a plunger and die arrangement of relatively simple and dependable construction.

containing parts which are few in number and so arranged that it is practically impossible for them to get out of adjustment. This is a feature of considerable importance in machines installed in a customers plant where the production of the box forming machine is used immediately for the packaging of goods produced, or processed in a continuous manner. It is evident that in such plants the dependability of the box machine is a factor of even greater importance than the dependability of a box ma chine operating in a boxmakers plant, since the production of the box machine is not stocked, but is used immediately.

The improved corner construction is not limited to use in corrugated boxes, but may equally advantageously be used for boxes of plain board, particularly low cost board such as chip board having relatively poor bending qualities.

These and other objects, features and advantages of the invention will appear more fully from a consideration of the detailed description which follows, accompanied by drawings, showing, for the purpose of illustration, a preferred embodiment and application of this invention.

The invention also consists in certain new and improved details of construction as hereinafter set forth and claimed. Although the characteristic features of the invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention, its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

Figure 1 is a plan view of a corner portion of a flat box blank embodying the invention, the outside surface of the blank facing the observer;

Figure 2 is a perspective view of the inside of a box cornet in its initial stage of assembly from the box blank shown in Figure 1;

Figure 3 is a perspective view of the outside of the box corner assembly of Figure 2;

Figure 4 is a perspective view of the outside of a box corner assembly at a further advanced stage of assembly;

Figure 5 is a perspective view of the outside of the assembled box corner;

Figure 6 is a perspective view of the inside of the box corner prior to the movement of a detaining tongue into final position;

Figure 7 is a perspective view of the inside of the completed box corner; and

Figure 8 is a plan view of a representative form of an entire box blank incorporating the box corner construction shown in the preceding figures.

In the following description and in the claims various structural details will be identified by specific names for convenience. The names, however, are intended to be as generic in their application as the art will permit.-

- may be applied to other structures than the ones shown.

turesof the invention, the improved corner construction is illustrated as applied to a blank of corrugated box board, it being understood that other types of board may be used with equal advantage.

The blank A is subdivided by scored fold lines and cuts into a plurality of panels, flaps, and tongues articulated to one another.

A main panel 11 is bounded by main fold lines 12 and 13. A first wall panel 14 is articulated to the main panel 11 along the main fold line '12 anda second wall panel 15 is articulated to the main panel along the main fold line 13. A flap 16 is articulated to the wall panel 14 along a first side foldline 17 and an external tongue 18 is articulated to the other wall panel 15 along a second side fold line 19. As will later be seen, the side fold lines 17 and 19 lie in substantial coincidence in the finished box corner, disregarding the necessary and customary offsets employed to compensate for the thickness of the board.

The second side fold line 19 is offset with respect to the cut side'edge 20=of the wall panel 15 by a distance d approximately equal to the thickness of the board. The external tongue 18 has an abutment edge 21 which is substantially in line with the edge 20, and also substantially in line, for all practical purposes, and parallel with, the side fold line 19, particularly in the case of low caliper board. In the illustrated embodiment the offset d is shown exaggerated for the sake of clearness. The external tongue 18 is cut from the stock of the flap 16 and extends towards the flap 16 with its point 22, both inthe flat blank and during the process of assembly.

The flap comprises aninternal tongue 23 cut from its stock and is articulated to the remainder of the flap 16 along a tongue fold line 24 which is preferably, but

not necessarily parallel to the side fold line 17. The

configuration of the internal tongue 23 is preferably such as to form a cut edge 25 on the flap 26 which runs obliquely with respect to the side fold line 17. It is evident that deflection of the internal tongue 23'out of the plane of the flap 16 results in an aperture 23 in the fiap through which, as will later be shown, the external tongue 18 may be inserted. The internal tongue 23 has a bordering external abutment edge which is preferably, although not necessarily, parallel to the tongue fold line 24. This external abutment edge 26 is conveniently formed by a cut spaced from the side fold line 17 by a distance d equal to the thickness of the board, or slightly more. Further cuts 27 and 28 extend from the edge 26 to the side fold line 17, thus bordering a tenon 29 integral with the first wall panel 14 and cut from the stock of the flap 16.

It is clearly seen that folding of the flap 16 with respect to the wall panel 14 produces a self opening aperture in the panel 16 adjacent the side fold lines 17 in which aperture the external tongue 18 rests in the set-up corner, as will later become apparent. This aperture will here inafter be referred to as 29.

The length l of the tenon 29 is substantially equal to the length l of the fold line 19 at which a mortise type aperture 31 is formed by folding of the external tongue 18 into which the tenon 29 fits, as will later appear.

It is apparent that the illustrated layout of the box corner involves no more than cutting and creasing and does not involve stripping. This is an advantage which reduces the cost of the interlock considerably.

The setting up of the box structure may be carried out as follows:

The fiap 16 is folded with respect to the Wall panel 14 about the side fold line '17, and substantially simultaneously, or shortly thereafter, the wall panels 14 and 15 are folded with respect to the main panel 11 about their respective main 'fold lines 12 and 13. Substantially simultaneously with the folding of the wall panel 15 the external tongue 18 is folded about its fold line 19 with respect to the wall panel 15 and is guided to strike the internal tongue 23, thereby opening the aperture 23 CPL through which the external tongue 18 passes (Figure 2). The projecting tenon 29 assists in guiding the external tongue 18, as the tip 22 of the tongue enters the aperture 23'. Thereafter the curved edge 30 of the external tongue 18 strike the oblique edge 25 which further guides the external tongue, together with the inner surface of the wall panel 14 along which the tip 22 slides.

During the further advanced phase of the assembly the elements assume the position shown in Figure 4, which is the position shortly before the abutment or locking edge 21 of the external tongue 18 moves behind the portion of the flap 16 bordered by the edge 25 and the side fold line 17.

Figure 5 illustrates the assembled corner, as it appears from the outside. The tenon 29 fits into the mortise 31 in the panel 15 which is formed by folding of the external tongue about its set-back fold line 19. The flap 16 lies face-to-face with the panel 15.

Considering now the appearance of the cornerconstruction, as it appears from the inside, Figure 6 shows the faceto-face position of the flap 16 with the wall panel 15. It also illustrates the position of the external tongue 18, lying face-to-face with the wall panel 14 and engaging with its locking 01' abutment edge 21 the surface portion of the flap 16 bounded by the fold'line 17 and the oblique cut edge 25.

Figure 6 illustrates the box corner elements in theposition which they assume just prior to the folding of the internal tongue 23 back into the plane of the flap 16, or, in other words, into the aperture 23. This final operation causes the external abutment edge 26 of the internal tongue 23 to bear against the surface of the external tongue locking and detaining the external tongue in its flap engaging position.

Figure 7 shows the completed box corner as seen from the inside. Considering now the function of the various elements, it is seen that the wall panel 15 is prevented from moving outwardly under the pressure of box contents by the external tongue whichengages with its abutment edge 21 the surface abutment portion 32 of the flap between the fold line 17 and the edge 25. The box corner is reinforced in this respect by the flap 16 overlying the panel 15, the flap resisting outfolding by reason of its being attached to the panel 14 along the fold line 17.

The side panel 15 is prevented against infolding by reason of its engagement with the flap 16 and particularly by reason of its side edge 20 overlying the end edge of the panel 14. Pressure against the panel 15 from the outside is thus taken up by the panel 14 in the plane of the panel 14, which is considerably more effective, than if pressure on the panel 15 from the outside were to be resisted solely by the flap 16, tending to fold the flap 16 towards the inside of the box.

The panel 14 is secure against infolding under external pressure by reason of the engagement of the bottom edge of the flap 16 with the surface of the main panel 11. The panel 14 is prevented from folding outwardly under the pressure of box contents by the internal tongue 23 which bears against the external tongue 18 immediately adjacent the fold line 19 of the external tongue. This fold line 19 is not visible in Figure 7, but is shown in Figures 1 to 5.

The internal tongue thus performs a double function. It firstly locks ordetains the external tongue 18 in corner locking position. It secondly prevents outfolding of the panel 14.

The external tongue also performs a dual function. It firstly locks the corner in the assembled position of its elements, and it secondly prevents the wall panel 15 from being folded outwardly.

The flap 16 performs a triple function of first providing a locking abutment for the external tongue, secondly it prevents infolding of the wall panel 14 and, thirdly, .it reinforces the corner against pressure of the-box contents from the inside.

The preferred but not essential direction of the corrugations is shown in Figure 1 as well as in the perspective figures. It is evident that in the preferred layout the folding of the external tongue 18 is assisted by the corrugations, whereas the stiffness of the internal tongue about its fold line 24 is greater, since its fold line extends at right angles to the corrugations.

The invention thus provides an improved corner construction which is admirably suited for the assembly of the corrugated boxes, but it has equal merits, if applied to boxes of plain board. It is particularly advantageous if used on board having relatively poor bending qualities such as chip board or board of high caliper. It is obvious that the set-backs d and d illustrated in Figure 1 should be adjusted according to the thickness of the board. They are naturally less in the event plain board is used.

Figure 8 illustrates a simple blank comprising four corners resulting in a box bottom or box cover as the case may be. Evidently the improved corner lock is equally useful, if applied to other forms of boxes, regardless of whether such boxes have square corners or sloping corners, as is the case of baskets or some forms of trays.

Obviously various modifications, additions, omissions, substitutions and other changes are possible Within the scope of the invention Without departure from its principles.

What is claimed is:

1. An improved corner construction for folding boxes, particularly for corrugated boxes, for assembling in corner forming relationship a main panel, two wall panels articulated to the main panel along main fold lines forming an angle, and a flap articulated to one of the wall panels along a first side fold line, the flap being adapted to overlie the inside of the other Wall panel when the panels are in corner forming position, the corner construction including in addition to said main panel, said wall panels and said flap, an external tongue articulated to said other wall panel along a side fold line, said external tongue extending towards said flap and having an abutment edge substantially parallel with said second side fold line, and an internal tongue articulated to said flap along a tongue fold line, said internal tongue, upon deflection out of the plane of the flap, forming an aperture in the flap through which said external tongue is insertable into a position in which the abutment edge of the external tongue engages the surface of said flap adjacent said aperture, said internal tongue having an external abutment edge substantially parallel with and spaced from said first side fold line, thereby leaving a projecting tenon on said one wall panel when the flap is folded with respect to said one wall panel, said second side fold line of said external tongue being set back from the side edge of said other wall panel, thereby forming a mortise on said other wall panel when said external tongue is folded with respect to said other wall panel, said mortise and said tenon being of substantially equal width and equal spacing from the corner, said internal tongue engaging the surface of said external tongue with its external abutment edge, thereby locking said external tongue in a position in which said external tongue lies face-to-face with said one wall panel and in edge-tosurface engagement with the flap.

2. A corner construction as set forth in claim 1 in which the spacing of said external abutment edge from the first side fold line, and the set-back of the second side fold line from the side edge is at least equal to the thickness of the stock.

3. An improved corner construction for folding boxes, particularly for corrugated boxes, for assembling in corner forming relationship a main panel, two wall panels articulated to the main panel along main fold lines forming an angle, and a flap articulated to one of the Wall panels along a first side fold line, the flap being adapted to over-lie the inside of the other Wall panel when the panels are in corner forming position, the corner construction including in addition to said main panel, said Wall panels and said flap an external tongue articulated to said other wall panel along a second side fold line, said external tongue extending towards said flap in the flat blank and having an abutment edge substantially in line with the side edge of said other wall panel, and a second tongue articulated to said flap along a tongue fold line, spaced from the line of articulation of said flap, said flap having an aperture therein between said first side fold line and the end of said flap into which aperture said external tongue is insertable into a position in which the abutment edge of the external tongue engages the surface of said flap adjacent said aperture, said aperture being formed by a tenon on said one wall panel extending beyond said first side fold line, said tenon being cut from the stock of the flap, thereby providing a self-opening aperture in the flap adjacent said first side fold line when the flap is folded with respect to said one wall panel, said second tongue having a first external edge portion bordering said tenon substantially parallel with said first side fold line, considering said second tongue in the assembled corner structure, said second tongue further having an oblique edge forming an angle of more than degrees with said first edge portion, the end of said oblique edge being at a distance from the box corner proper not less than the far end of said abutment edge.

4. A box corner construction, particularly for corrugated board, comprising, in corner forming position, a main panel; two side panels articulated to the main panel; a flap articulated to the side of one of the side panels at the corner; an external tongue articulated to the other side panel at the corner along a fold line spaced from the side edge of said other side panel by approximately the thickness of the board, said tongue having an abutment edge substantially in line with the side edge of said other panel, and being further bounded by an upper cut edge and a lower cut edge meeting at the tip of the tongue, the lower cut edge extending in an upwardly sloping direction from said side edge, said upper cut edge being substantially arcuate and extending from said tip to the end of said abutment edge, said flap having an internal cut therein forming an internal tongue, said internal cut comprising a first portion substantially parallel to the line of articulation of said flap and spaced from said last named line by approximately the thickness of the stock, said internal out having a second portion forming an angle of more than 90 degrees with respect to said first portion and extending away from said one side panel, the radial distance of the far end of said second portion from the box corner proper being not less than the radial distance of the far end of the said abutment edge from the box corner proper; said internal cut defining an internal tongue in said flap directed towards said one side panel, said flap having a line of articulation along which the said internal tongue is attached to said flap, said internal tongue, upon deflection, forming an aperture into which said external tongue is insertable into locking position, said flap comprising an engagement area bounded by the aforesaid side of said one side panel and said second portion of said internal out, said engagement area being in surfacc-to-edge engagement with the abutment edge of said tongue.

5. An improved corner construction for folding boxes, particularly for corrugated boxes, for assembling in corner forming relationship a main panel, two wall panels articulated to the main panel along main fold lines forming an angle at the box corner proper and a flap articulated to one of the wall panels along a first side fold line, the flap being adapted to overlie the inside of the other wall panel when the panels are in corner forming position, the corner construction comprising, in addition to said main panel, said wall panels, and said flap, an external tongue articulated to said other wall panel along a second fold line constituting one side of the tongue, said external tongue further having an upper cut edge and a lower cut edge, the lower cut edge extending in an upwardly sloping direction from said second side fold line,

said external tongue having an abutment edge extending from said upper .cut edge substantially parallel to said second side fold iline towards the corner; and an internal tongue out from the stock of the said flap by an internal cut of bent outline, said out including a central cut portion substantially parallel to said first side fold line, a substantially straight upper cut portion extending at an obtuse angle from said central cut portion, the far end of said upper cut portion beingat a distance fromthe corner proper not less than the distance of the far end of the abutment edge of the external tongue from said corner, said internal cut further comprising a lower cut portion extending 'from said central portion at a point having a distance from the corner proper .not greater than the point at which the lower edge of said external tongue meets said second fold line, said internal tongue being articulated to said flap along a tongue fold line spaced from said first fold line, said internal tongue extending towards said one wall panel and, upon deflection out of the plane of the flap, forming an aperture in the flap .into which said external tongue is insertable into a position in which the abutment edge of .the external tongue engages the surface of said flap between said upper cut edge of said internal tongue and said first side fold line, said internal tongue further having an abutment edge formed by said central cut portion for engaging the surface of the external tongue in the position in which the external tongue lies face-to-face with said one wall panel, and in edge-to-surface engagement with said flap.

6. An .improvedcorner construction for folding boxes, particularly for corrugated boxes, for assembling in corner forming relationship a main panel, two wall panels articulated to themain panel along main fold'lines formingan .angle at the box corner proper and a flap articulated to one of the wall panels along a first side fold line, the flap being adapted to overlie the inside of the other wall panel when the panels are in corner forming position, the corner construction comprising, in addition to said main panel, said wall panels, and said flap, an external tongue articulated to said other wall panel along a second side fold line constituting one side of the tongue, said external tongue further having an upper cut edge and a lower cut edge, the lower cut edge extending in an upwardly sloping direction from said second side fold line, said external tongue having an abutment edge extending from said upper cut edge substantially parallel to said second side fold line towards the corner; and an internal tongue out from the stock of the said'fiap by an internal cut of bent outline, said cut including a central cut portion substantially parallel to, and spaced from, said first side fold line by a distance substantially equal to the thickness of the board, a substantially straight upper cut portionextending at an obtuse angle from said central cut portion, the far end of said upper cut portion being at a distance from the corner proper not less than the distance of the far end of the abutment edge of the external tongue from said corner, said internal cut further comprising a lower cut portion extending from said central portion at a point having a distance from the corner proper not greater than the point at which the lower edge of saidexternal tongue meets said second fold line, said internal tongue being-articulated to said flap along a tongue fold line spaced from, and substantially parallel to, said first side fold line, saidcentral cut portion forming a substantially straight abutment edge on said internal tongue, said internal tongue extending towards said one wall panel and, upon deflection'out of the plane of the flap, forming an aperture in'the flap into which said external tongue-is insertable into a position in which the abutment edge of the external tongue engages the surface of said flap between said upper cut edge of said internal tongue and said first side fold line, said internal tongue further engaging the surface of said external tongue with its said abutment edge in the position in which the external tongue lies face-to-face with said one wall panel and in edge-to-surface engagement with said flap.

References Cited in the file of this patent UNITED STATES PATENTS 714,138 Brown Nov. 25, 1902 885,159 Keys Apr. 21, 1908 1,682,165 Boeppler Aug. 28, 1928 1,713,154 Williams May 14, 1929 2,445,034 Moore July 13, 1948 2,476,253 Van Rosen July 12, 1949 

